WEIGHING AND SORTING ROLLER BELT CONVEYOR

Description

BACKGROUND

[0001] The invention relates generally to power-driven belt conveyors. In particular, it relates to conveyors in which articles are weighed on a conveyor belt having rollers that are selectively actuated to direct articles along different paths according to their weights.

[0002] Conveyor belts are often used to convey products through weighing stations such as checkweighers. If a product's weight is outside an acceptable range, the product is separated from the acceptable products. The separation is typically achieved by positioning a rejector downstream of a weighing station to divert rejected, out-of-range products to a reject conveyor for corrective action. The transfer of products from one device-the weighing system-to a second device-the rejector-can cause positioning errors that result in false rejects. And using two separate devices adds complexity and risk.

[0003] WO 2016 / 196087 A1 discloses a weighing system according to the preamble of claim 1 and a conveyor belt according to the preamble of claim 12. has electrically conductive rollers that are rotated with a constant torque in a lateral direction by a linear induction stator defining a roller-activation zone along a carryway. Because the lateral acceleration of a conveyed object is inversely proportional to the object's weight, lighter objects are displaced farther and at greater speeds than heavier objects. So their weights can be determined from the lateral acceleration, speed, or displacement. And objects can be sorted off the side of the belt by weight.

[0004] US 7 344 018 B2 discloses a conveyor and associated method for diverting closely spaced articles conveyed along the conveyor. The conveyor includes a conveyor belt with belt rollers oriented to rotate on axes oblique to the direction of belt travel. A series of arrays of bearing surface elements are arranged end to end along the length of the conveyor. The bearing surfaces may be static or rotational. Each array defines a roller-control zone in which the array is selectively activated with its bearing surface elements in contract with the belt rollers or deactivated with its bearing surface elements out of contact with the belt rollers. As the belt advances through an activated roller-control zone, the belt rollers rotate to propel a conveyed article toward a side of the belt. The contiguous roller-control zones are sequentially activated and deactivated to direct articles to the side and off the belt or to let them pass straight through. The length of the entire series of roller-control zones determines the lateral extent of the sidewise diversion. The length of each roller-control zone determines the minimum gap between consecutively conveyed articles. The serial cascade of these roller-control zones permits the tight sortation of closely spaced articles for high throughput.SUMMARY

[0005] In one aspect, the present invention provides a weighing system in accordance with claim 1.

[0006] In another aspect, the present invention provides a conveyor belt in accordance with claim 12.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a perspective view of one version of a weighing system embodying features of the invention. FIGS. 2A and 2B are enlarged isometric and side views of a belt roller with an embedded weight sensor usable in a weighing system as in FIG. 1. FIG. 3 is a side perspective view of a belt module partly cut away with an embedded weight sensor usable in a weighing system as in FIG. 1. FIG. 4 is a perspective view of a weighing system as in FIG. 1 in a switch configuration. FIGS. 5-7 are schematic block diagrams of three versions of systems for collecting weight data in the weighing system of FIG. 1. DETAILED DESCRIPTION

[0008] One version of a weighing system embodying features of the invention is shown in FIG. 1. The weighing system 10 includes a conveyor belt 12 advancing along a travel path from an upstream end 14 to a downstream end 15 in a travel direction 16. The conveyor belt 12 is a roller belt having a plurality of article-supporting belt rollers 18 extending above the belt's outer face. The belt rollers 18 shown in FIG. 1 are arranged to rotate on axes 20 oblique to the travel direction 16. One example of roller belt with obliquely rotatable rollers is disclosed in U.S. Patent No. 6,968,941, "Apparatus and Methods for Conveying Objects," Matthew L. Fourney, Nov. 29, 2005. Commercial versions include the INTRALOX ®< Series 400 Angled Roller Belt manufactured and sold by Intralox, L.L.C. of Harahan, Louisiana, U.S.A. Another example of a roller belt is disclosed in U.S. Patent No. 7,506,751, "Conveyor Systems for Diverting Objects," Matthew L. Fourney, Mar. 24, 2009. The rollers described in that patent rotate on axes parallel to the travel direction. Commercial versions include the INTRALOX ®< Series 7000 Belt. Yet another roller belt is the ball belt disclosed in U.S. Patent No. 7,216,759, "Conveyor Belt Modules with Embedded Spherical Rollers Retained in the Modules," Brien G. Rau et al., May 15, 2007. The spherical rollers described in that patent rotate about all axes. Commercial versions include the INTRALOX ®< Series 400 Ball Belt. Or the rollers can be stacked oblique rollers in which a bottom roller is actuated to rotate a top article-supporting roller in the opposite direction. A roller belt with stacked rollers is disclosed in U.S. Patent No. 7,360,641, "Conveyor Belt Having Rollers that Displace Objects," Matthew L. Fourney, Apr. 22, 2008. Commercial versions include the INTRALOX ®< Series 4550 DARB Belt.

[0009] An infeed conveyor 22 feeds articles 24 onto the roller belt 12 at the upstream end 14 of the weighing system 10. The articles 24 sit atop the rollers 18 and are conveyed along a first length of the travel path through a weighing zone 26. Because the belt rollers 18 are not actuated in the weighing zone 26, the articles 24 pass through the weighing zone without being diverted from the travel direction 16 by the rollers. The articles 24 are weighed as they pass through the weighing zone 26. The conveyor belt 12 then conveys the articles into a second length of the travel path defined by a roller-actuation, or sorting, zone 28 downstream of the weighing zone 26. In this version the roller-actuation zone 28 comprises two sequential roller-actuation subzones 28A, 28B. Actuators 30 in the roller-action zone 28 are selectively actuated and deactuated as a function of the weights of the articles atop the rollers. For example, when actuated, the actuator 30 causes the belt rollers 18 to rotate on their axes 20 oblique to the travel direction and to push articles, such as out-of-range articles 24A, 24B whose weights are outside a predetermined acceptable weight range, off the side of the belt and onto reject conveyors 32A, 32B. Weights outside the acceptable weight range can be can be divided into two or more unacceptable subranges. For example, the two roller-actuation zones as in the version shown in FIG. 1 could each correspond to one of two unacceptable weight ranges. All the out-of-range articles 24A whose weights are less than a predetermined unacceptable weight could be diverted in the first roller-actuation subzone 28A, and all those articles 28B whose weights exceed the predetermined unacceptable weight could be diverted off in the second subzone 28B. The rollers 18 supporting acceptable in-range articles 24" are deactuated as they pass through the roller-actuation zone 28. The acceptable articles are delivered over the conveyor's downstream end 15 to a discharge conveyor 34A, 34B. In that way rejected out-of-range articles 24A, 24B exit the conveyor belt 12 along a different path from the in-range articles 24C. And because a single conveyor belt 12 conveys the articles 24 through both the weighing zone 26 and the roller-actuation zone 28 without intervening belt-to-belt transfers, false rejects due to positioning errors are reduced. More than two roller-actuation subzones could be used to sort out-of-range articles to multiple reject conveyors according to out-of-range weight subranges into which they fall. Or the sorting can be organized according to other criteria, such as destination and package type, as just two examples.

[0010] FIGS. 2A and 2B show a belt roller 18 with a weight sensor to measure the weights of articles. The cylindrical roller 18 is mounted on an axle 36 that defines the roller's axis of rotation 20. The weight sensor comprises three load cells 38, which are connected between the roller's periphery 40 and a hub 42 surrounding the axle 36. The three load cells 38 in this example are equi-spaced around the axle 36. The load cells 38 are electrically connected to associated support circuitry 44. The three load cells 38 resolve the downward force F, which is proportional to the weight of an article sitting atop the roller. The sums of the downward forces on all the rollers supporting an article equal the article's total weight.

[0011] Instead of being incorporated into the rollers as in FIGS. 2A and 2B, the weight sensor shown in FIG. 3 is embedded in the conveyor belt. The conveyor belt 12 shown in FIG. 1 is a modular conveyor belt constructed of a series of rows 46 of one or more belt modules, such as the module 48 shown in FIG. 3. The rows 46 are hingedly linked together by hinge rods 49 at hinge joints. In this version the roller 50 is mounted on an axle 52 that is oriented parallel to the travel direction 16. The ends of the axle 52 are supported from below on load cells 54, 55 embedded in the module 48. A downward force F on the article-supporting roller 50 is measured by the two load cells 54, 55. The sum of the outputs of the two load cells 54, 55 equals the applied force F. Like the load cells in FIGS. 2A and 2B, the load cells 54, 55 in FIG. 3 are associated with support circuitry to be described later.

[0012] The weighing system 94 shown in FIG. 4 is operated as a conveyor switch. A roller conveyor belt 96 is divided across its width into two parallel longitudinal lanes 98, 99 that extend from the upstream end 14 to the downstream end 15. The infeed conveyor 22 feeds articles 24 onto the first lane 98 at the upstream end 14 of the conveyor belt 96. The articles 24 are weighed in the first lane 98 in the weighing zone 26. The roller-actuation zone 28 is selectively actuated either only for articles 24 whose weights are in-range or only for articles whose weights are out-of-range. When selectively actuated, the belt rollers 18 divert the articles from the first lane 98 to the second lane 99. Thus, the selectively diverted articles 24' are switched to the second lane 99 to exit the downstream end 15 of the conveyor belt 96 onto a discharge conveyor 101. The roller-actuation zone 28 is deactuated for articles 24" that are not selected to be switched to the second lane 99. Instead, those articles 24" remain in the first lane 98 to exit onto a separate discharge conveyor 102. In another version the conveyor belt comprises two side-by-side abutting conveyor belts, in which the second conveyor belt can be, but does not have to be, a roller belt.

[0013] Various ways of collecting and using the weight measurements for weighing conveyors in which the weight sensor is integrated into the conveyor belt or its rollers are shown in FIGS. 5-7. FIG. 5 represents a passive system in which the belt has only passive components. A load cell 64, such as a load cell 38 as in FIGS. 2A and 2B or a load cell 54, 55 as in FIG. 3, in the belt 12 is electrically connected to a transmitter 66 realized as a capacitor plate or a coil. A receiver 82 external to and below the belt 12 in the weighing zone is realized as a second capacitor plate forming a capacitor with the plate in the belt or as a second coil forming a transformer with the coil in the belt. Thus, the weight sensor's weight signal 70 is sent by the transmitter 66 to the external receiver 82 by capacitive or inductive coupling when the sensor 64 is in the weighing zone. The received weight signal is conditioned, including being converted from an analog weight signal 70' into a digital weight signal 71 in a conditioning circuit 72 before being sent to a controller 74, which may be realized as a programmable logic controller or other programmable computing device executing program steps stored in a program memory. The controller 74 also receives weight signals from other weight sensors and, from those signals, determines the weight of an article, compares its weight to a predetermined weight range, classifies the article as out-of-range if its weight is outside the weight range or as in-range if within, and selectively sends an actuation signal 76 to the actuator 30 in the actuation zone for either only the out-of-range articles or only the in-range articles to rotate the belt rollers to divert the in-range and out-of range articles off the belt along different exit paths.

[0014] Another version of support circuitry to transmit weight signals from the belt to the external controller 74 is shown in FIG. 6. The circuitry on board the belt 12 includes the load cell 64, a local controller 78, and a transmitter 80. The analog weight signal 70 is converted to a digital weight signal 71 by the controller 78 and an associated analog-to-digital converter. The digital weight signal 71 is then transmitted by the transmitter to an external receiver 82 while the weight sensor is in the weighing zone. The received digital weight signal 71' passes through an interface circuit 84 on its way to the controller 74, which determines the weight of the article and either actuates or deactuates the belt rollers as they convey the article through the roller-actuation zone. The belt-borne components receive power from an external power supply 86, which is coupled to a power receiver 88 including a voltage regulator, in the belt. Power transfer to the power receiver 88 can be by inductive or capacitive coupling, by light transmission, or by sliding electrical contacts, as just a few examples.

[0015] Yet another version of support circuitry is shown in FIG. 7, which is similar to FIG. 6, except that FIG. 7 shows a storage element 90, such as one or more dry cells or capacitors, powering the weight-sensor circuit. The external power source 86 is optionally coupled to a local charging circuit 92 in the belt to recharge the rechargeable storage element 90 wirelessly or via contacts.

[0016] Although the invention has been described in detail with regard to two versions, other versions are possible. For example, not all the rollers have to be weighing rollers. As another example, the in-range rather than the out-of-range articles could be diverted off the side of the belt while the out-of-range articles pass straight through the roller-actuation zone and off the end of the belt. For belts with roller balls or rollers on axles parallel to the travel direction, the rollers can be actuated to divert in-range articles off one side of the belt and out-of-range articles off the other side. And different kinds of roller-actuation mechanisms can be used. For example, a flat plat that is movable up and down into and out of contact with the belt rollers by a linear actuator can be used to actuate and deactuate the oblique belt rollers. Or the mechanism can raise and lower long actuating rollers whose axes of rotation are parallel to the travel direction into and out of contact with the oblique belt rollers to actuate and deactuate them. For use with belt rollers whose axes of rotation are parallel to the travel direction, the roller-actuating mechanism can use shorter caster rollers whose axes of rotation are oriented oblique left or right to the travel direction to rotate the belt rollers to push articles off one side of the belt or the other. Or the rollers can be made of electrically conductive or magnetic materials with poles and selectively actuated by a linear-motor stator in the roller-actuation zone. So, as these examples suggest, the invention is not meant to be limited to the exemplary versions described in detail.

Claims

1. A weighing system (10) comprising: a conveyor belt (12; 56) arranged to advance in a travel direction (16) along a travel path from an upstream end (14) to a downstream end (15) and having a plurality of article-supporting rollers (18; 50; 58) actuatable to rotate toward a side of the conveyor belt (12; 56) in a transverse direction transverse to the travel direction (16); a weighing zone (26) extending along a first length of the travel path in which one or more weight sensors measure the weights of articles (24) conveyed by the conveyor belt (12; 56) and produce weight signals (70) indicative of the weights of the articles; a roller-actuation zone (28) extending along a second length of the travel path; wherein, in the roller-actuation zone (28), an actuator (30) selectively actuates the article-supporting rollers (18; 50; 58) as they pass through to push articles (24) in the transverse direction; characterised in that the weighing system (10) comprises a controller (74): receiving the weight signals (70); determining the weights of the articles (24) from the weight signals (70); selectively actuating and deactuating the rollers (18; 50; 58) passing through the roller-actuation zone (28) as a function of the weights of the articles (24); wherein the weight sensors are coupled to the rollers (18; 50; 58) to measure the downward forces (F) on the rollers (18; 50; 58) applied by the conveyed articles (24) atop the rollers (18; 50), the weight signals (70) being proportional to the downward forces (F).

2. A weighing system (10) as in claim 1 wherein a) the roller-actuation-zone (28) along the second length is downstream of the weighing zone (26) along the first length: b) the roller-actuation-zone (28) along the second length overlaps the weighing zone (26) along the first length; or c) the roller-actuation-zone (28) and the second length coincide with the weighing zone (26) and the first length.

3. A weighing system (10) as in claim 1 wherein the controller (74) compares the weights to a predetermined weight range, classifies articles whose weights are outside the weight range as out-of-range articles and articles whose weights are within the weight range as in-range articles, and actuates the article-supporting rollers (18; 50) passing through the roller-actuation zone (28) to rotate in the transverse direction either for only the out-of-range articles or for only the in-range articles, whereby the out-of-range articles and the in-range articles exit the conveyor belt (12) along different paths.

4. A weighing system (10) as in claim 3 wherein the conveyor belt (12) has adjacent first and second lanes (98, 99) extending from the upstream end (14) to the downstream end (15) and wherein the weighing system (10) comprises: an infeed conveyor (22) feeding articles (24) onto the first lane (98) of the conveyor belt (12) at the upstream end (14); wherein only the first lane (98) extends through the weighing zone (26); wherein the controller (74) actuates the article-supporting rollers (18; 50) passing through the roller-actuation zone (28) for either only the out-of-range articles or only the in-range articles to direct either only the out-of-range articles or the in-range articles to the second lane (99).

5. A weighing system (10) as in claim 1 comprising a plurality of roller-actuation subzones (28A, 28B) in the roller-actuation zone (28) or comprising a plurality of roller-actuation subzones (28A, 28B) in the roller-actuation zone (28) and wherein the controller (74) compares the weights to a plurality of predetermined weight ranges each corresponding to one of the roller-actuation subzones (28A, 28B) and actuates the article-supporting rollers (18; 50) passing through the roller-actuation subzone (28A, 28B) corresponding to the weight range each article's weight falls in.

6. A weighing system (10) as in claim 1 wherein either: (a) the conveyor belt (12) includes axles (36; 52) defining axes (20) parallel or oblique to the travel direction (16) about which article-supporting rollers rotate (18; 50); or (b) the rollers are stacked rollers.

7. A weighing system (10) as in claim 1 wherein the controller (74) is external to the conveyor belt (12).

8. A weighing system (1) as in claim 7 further including receivers (82) external to the conveyor belt (12) and wherein the weight sensors are mounted in the conveyor belt (12) to measure the weights of the articles (24) on the rollers (18; 50) and wherein the conveyor belt (12) includes transmitters (80) that receive the weight signals (70) from the weight sensors and transmit the weight signals (70) to the receivers (82), which send the weight signals (70) to the controller (74).

9. A weighing system (10) as in claim 8, wherein the weight sensors and the transmitters (80) reside in the rollers.

10. A weighing system (10) as in claim 8, wherein the conveyor belt (12) includes axles (52) on which the rollers (50) are mounted and wherein the weight sensors are connected between the ends of the axles (52) and the conveyor belt (12).

11. A weighing system (10) as in claim 8, wherein the conveyor belt (12) includes local controllers (78) between the weight sensors and the transmitters (80) converting the weight signals (70) into digital weight signals (71) transmitted by the transmitters (80) to the receivers (82).

12. A conveyor belt (12) comprising: a series of rows (46) of one or more belt modules (48) hingedly linked together; a plurality of article-supporting rollers (50) mounted in the belt (12); characterised by a plurality of weight sensors coupled to the rollers (50) to measure the downward forces (F) on the rollers (50) applied by articles (24) atop the rollers (50) and to produce weight signals (70) proportional to the downward forces (F).

13. A conveyor belt (12) as in claim 12 wherein the weight sensors are mounted in the rollers (50); or further comprising a plurality of axles (52) on which the rollers (50) are mounted for rotation and wherein the weight sensors are connected to the ends of the axles (52).

14. A conveyor belt (12) as in claim 12 comprising transmitters (66; 80) receiving the weight signals (70) produced by the weight sensors and transmitting the weight signals (70).